The encoder is the "eye" of the machine — it turns mechanical position and speed into electrical signals. The two mainstream types on the market — optical encoders and ring (magneto-electric) encoders — differ in principle and are suited to different scenarios. Choosing wrong can mean frequent failures or unmet accuracy. This article explains it simply.
1. Difference in Principle
- Optical encoders: count light/dark grating patterns on a disk via an emitter and receiver. High accuracy and fast response, but the optical path is sensitive to oil, dust and vibration.
- Ring (magneto-electric) encoders: a magnetic head reads the magnetic scale on a ring — inductive measurement. KOSEND DA series uses magneto-resistive scanning, reading scales over 0.5mm pitch; the scan unit is fully potted and resistant to oil, water and dust.
2. Key Indicator Comparison
| Dimension | Optical | Ring Magnetic |
|---|---|---|
| Accuracy | High (fine gratings) | Medium-high (DA TTL up to 150k pulses, customizable) |
| Pollution resistance | Poor — fails when the optical path gets dirty | Excellent — fully potted, unaffected by oil/dust |
| Shock & vibration | Fair — disk can break | Excellent — solid metal body withstands impact |
| Speed | High | High (DA supports 60,000 r/min) |
| Large bore mounting | Difficult | Excellent (DA bore 0-260mm customizable) |
| Cost | Higher | More economical |
3. How to Choose?
- CNC spindle, lathe C-axis, rotary tables: heavy oil, vibration, large bore required → ring magnetic encoders (e.g. KOSEND DAG/DAW/DAT/DAP) — this is the choice of many machine builders.
- High-precision measurement, labs, light-load environments: optical encoders have a clear accuracy advantage.
- Servo motor feedback: both are used; magnetic types win on pollution resistance and cost.
4. Summary
No absolute "better" — only the right working condition. If your environment has oil mist, chips or dust, or you need large-bore mounting, a magnetic ring encoder is the more reliable choice. KOSEND ring encoders support RS422 (TTL square wave) and 1Vpp (sine/cosine) output; pulse counts and bore sizes are customizable. Call 400-100-6802 for selection advice.